Drive control mechanism for prime mover with fluid actuated clutches



Feb. 16, 1960 A. F. GRANT ETAL 2,925,156;

DRIVE CONTROL. MECHANISM FOR PRIME MOVER l WITH FLUID ACTUATED CLUTCHESFiled Dec. 24, 1957 6 Sheets-Sheet 1 CLUTCH .s2/P

7U CLUTCH y"T4/.Q SUPPLY ENG/NE ROOM CO/VTRL SWT/01V mun/WAL za/vf PILOTHOUSE CO/VTPDL Feb. 16, 1960 A. F. GRANT ETAL 2,925,156

DRIVE CONTROL MEcHANIsM Foa PRIME MovER WITH FLUID ACTUATED cLuTcHEsFiled Dec. 24, 1957 6 Sheets-Sheet 2 INVENTORS A. F. GRANT ET AL DRIVECONTROL MECHANISM FOR PRIME MOVER Feb. 16, 1960 WITH FLUID ACTUATEDcLUTcx-IES 6 Sheets-Sheet 3 Filed Dec. 24, 1957 Mm o e 1.... E M Z fw wum 5 W my E uw.. 5 N A F U ,al E E C M ../v ma Amr 6 v/w y ,Mm wam w M 6W w E W L 5 UAA p AE MW Mp6 c MN 5 Ma www w A my m .4m m .f MR 3N 7H M E0 M 2 M mlmw Y T Y Umlmm m w w m Sum mlw nog E .G o mi wm E M. 0 W m Hmw ,NEM RP 5X Ew Ul 0 an m e v m w m .w m. w o

maaar/nm TIME- Ml SECGNDS Feb. 16, 1960 A. F. GRANT ET AL 2,925,156

DRIVE CONTROL MECHANISM FOR PRIME MOVER WITH FLUID ACTUATED CLUTCHES 6Sheets-Sheet 4 Filed Dc. 24, 1957 SUPPLY HS TEEN cL urcf/ INVENTORS ATUR/VE Y Feb. 16, 1960 A. F. GRNT ETAL DRIVE CONTROL MECHANISM FOR PRMEMOVER Filed Dec. 24, 1957 WITH FLUID ACTUATED CLUTCHES 6 Sheets-Sheet 5Feb. 16, 1960 A. F. GRAN-r Erm.

DRIVE CONTROL MECHANISM FOR PRIME MOVER WITH FLUID ACTUATED CLUTCHESFiled Dec. 24, 1957 6 Sheets-Sheet 6 Em bkb NU QN ,SNT

(JLMR INVENToRs @zaga/z Gao/)ff Blf/70d??? nited States aten 4 2,925,156DRIVE CONTROL MECHANISM FOR PRIME MovER wIrH FLUID AcrUArnn cLUreHEs F,Grant, Cleveland, and Robert R. King, Lakewood, Ohio; said Grant`assgnor to General Motors Corporation, Detroit, Mich., a corporation of'Delaware' Appiieaton December 24, 1957, Serial No. 705,006

This invention relatestocontrol apparatus of the tiuid pressure type forselectively controlling the speed of a unidirectional prime mover andthe selective operation of clutches for controlling the speed anddirection of an output member and has particular application tomaneuvering control systems for marine propulsion drives.

Where a prime mover on a ship is operative in one direction only, it iscustomary to employ either a reversible electrical drive or forward andreverse clutches for selectively controlling the rotational direction ofthe propeller and hence the propulsion of the ship in either the forwardor the astern directions. Prior to the instant invention, the operatingcharacteristics of reversible electrical drives have generally beendeemed to be much superior to those of reversible clutch drives,providing a responsiveness, a fneness, and an adaptability of controlnot considered possible with a clutch drive. However, such electricaldrives andthe controls therefor are relatively complex and expensive.Hence, reversible clutch drives have been utilized `quite extensively inthose applications where a high degree of neness and responsiveness` ofcontrol have not been required. VWith such clutch drives it is of coursenecessary to match the starting and running torque characteristics ofthe individual clutches with the speed and torque characteristics of theprime mover.

To reverse the direction of operation of the propeller with a reversingclutch drive, it is only necessary to disengage the one clutch and tosubsequently engage the other. However, to minimize the powerdissipation or work imposed on theoncoming clutch and thereby clutchWear and to prevent damage to the clutches on other parts of the powertransmitting mechanism upon clutch engagement, it has generally beendesirable that the prime mover and the propeller rst be brought to andmaintained at a low speed such as the idling speed of the prime moverbefore disengagement of the operating clutch and energization of theother clutch for engagement. To minimize' the possibility of stallingthe engine during such low engine speed clutch engagement the engineidle fuel setting has necessarily been established at a rate higher thanthat which would otherwise have been required thus reducing overalloperating eiciency of the power plant or provision has been made in thecontrol mechanism for advancing the engine fuel setting slightly aboveits idle rate during the clutch engaging period.

The invention contemplates the provision of a simple, rugged, foolproofand relatively inexpensive marine drive and control system for a primemover having speed setting means and ahead and astern driving clutchesand including an improved single-lever maneuvering control mechanisminterconnecting the speed setting means and clutches and adapted toprovide controlled clutch engage ment comparable in smoothness andcontrollability to an electrical drive' and further to provide acontrolled increase-in the speed setting of the prime mover and in thetorque transmitting capacity of the engaged clutch after 2,925,156Patented Feb. te, i960 initial full engagement of either clutch inresponse to manual movement of the manuvering control lever between aneutral zone and full speed ahead and astern contro;ling positions.

The combined means by which the foregoing objectives are accomplished,together with other novel. features and advantages of the invention,will become more apparent from the following detailed description ofseveral embodiments thereof having reference to the accompanyingdrawings in which:

Figures l and la are diagrammatic views, partly in section and partly inoutline, of complementary portions of an engine speed and clutchengagement control mechanism embodying the invention;

Figure 2 is a` graph showing the interrelationship between engine andoutput shaft speed and clutch ination pressure for the embodiment of theinvention shown in Figures l and la;Y

Figure 3 is a graph showing the operating cycle of the form of theinvention of Figures l and la in a full ahead and full asternreversal;

Figure 4 is a graph similar to Figure 3 showing a full' astern to fullahead reversal; and

Figures 5 to 8 are diagrammatic views showing modi'- fied forms of theinvention.

DESCRIPTIONQFIGURE 1e Referring `more particularly to Figure la, atwo-way reverse clutch is indicated generally at 10 and includes anahead coupling 11 andan astern coupling 12; The two coupling units areselectively energizable to drivingly interconnect a unidirectionalengine 14 to a propeller drive shaft loof a ship to provide eitherforward or reverse drive, respectively, through a suitablereverseand-reduction gear mechanism 18. The coupling units areindependently operable by fluid pressure and in a first range ofoperation are adapted to provide controllable slip of the propellershaft relative to the driving engine, the speed of the output shaftbeing substantially proportional to the actuating pressure appliedthereto up to a given pressure `at which either coupling is normallyfully engaged under engine idle speed and load conditions. Furtherincrease in the actuating pressure supplied to either coupling abovesuch a given pressure serves to further increase the speed and torquecapacity of the coupling unit. g

The two-way reverse clutch 10 includes a driving input assembly commonto both the forward and reverse couplings. This driving assemblycomprises an engine driven stub shaft 20, a driving spider or disk 21,an annular drive adapter 22, and a driving drum or housing includingannular end plates 23, 24 and intermediate members 25, 26, all of' whichare secured together by suitable means. The intermediate housing membersZ5 and 26 have outer cylindrical portionsextending axially from the `endplates 23 and 24 and adjacent end portions which `extend radiallyinwardly to provide ltwo flanges in spaced parallel relation to the endplates 23 and 24. The members 23, 24 and 25, 26 thus define two annularrecesses for mounting the coupling units 11 and 12.

The coupling units 11 and 12 each includes two axially spaced annularclutch plates 28, 29 and 310, 31, respectively, which are externallysplined to the housing members 25 and 26, respectively. These clutchplates carry shoes of suitable rictional material and are adapted tofrictionally engage clutch plates 32 and 33, respectively, which aresandwiched therebetween. The clutch plate 32 is internally splined to anahead drive hub 34 and the clutch plate 33 is similarly splined to areverse drive hub 35. The ahead drive hub 34 is drivingly connected to ahollow input drive shaft 36 of the reverse-and-reduction gear unit 18.The reverse drive hub 35 is journaled on the s haft 36 by spacedantifriction bearings 37, 38 and is drivingly connectable to the inputdrive shaft 36 and the propeller shaft 16 bya conventionalreversing-andreduction gear mechanism within the gear unit 18, a bevelgear of a differential type reversing gear being partially shown at 39.The drive plates 28, 29 and 30, 31 are adapted to be biased intofrictional driving engagement with the output drive plates 32 and 33 bythe selective inflation of two annular tubes 40 and 41 carried by thedrive housing end plates 23 and 24. The axial expansion of the tubes 40and 41 is transmitted to the several clutch plates through intermediateheat-insulating plates 42 and 43. To insure disengagement of the severalclutch plates whenever the tubes 40 and 41 are vented to atmosphere, aplurality of radially and equi-angularlv spaced springs 44 are adaptedthrough a plurality of radially extending iingers or spokes 45 to biasthe menibers 42 and 43 out of drive maintaining engagement with theadjacent clutch plates.

The clutch plates 42 and 43 are radially slotted to provide a pluralityof radial ribs 42' and 43' which are adapted to thrustablv engage theadjacent surface of the drive plates 2,9 and 31 and define a pluralityof radially extending passages therebetween. The inwardlv extendingflange portions of the housing members 25 and 26 are similarlv slottedto provide radial passage-defining ribs 25 and 26 engaging the adjacentsurfaces of the drive plates 29 and 30, The drive plates 32 and 33 arealso provided with a plurality of radially extending cored passages 32'and 33'. The several passages thus defined intermediate and within theseveral clutch plate elements open on radially extending passages orports in the cylindrical portion of the housing members 25 and 26 andupon rotation of the several clutch members these passages serve asradial impellers inducing7 the rapid flow of cooling air therethroughthus dissipating the heat generated during the clutch engaging process.

Fluid under pressure is supplied to and discharged from the clutchactuating tubes 40 and 41 by way of two iiexible air tubes 46 and 47,respectively, which are in turn connected to air supply passages 48 and49 provided in an air supply tube or shaft 50. The air supply shaft 50is journaled in and proiects from the ends of the hollow input driveshaft 36 yof the gear mechanism. The engine end of the air supply tube50 is drivingly connected to and supported by the input driving assemblyof the clutch unit 10. a plate 51 carried bv the driving spider 21 andthe ange end of the stub shaft 20 being universally connected to theadjacent end of the air tube 50 as indicated at 52. The passages 48 and49 terminate adjacent the opposite end of the air tube in two axiallyspaced ports 48 and 49', respectively. These ports register with annulargrooves 54 and 55. respectively, which are formed in a fluid seal member56 journaled on the end of the air tube shaft. The annular grooves 54and 55 are in turn connected to two inflation pressure supply pipes 101and 102, respectively.

The engine 14 is provided with an engine driven centrifugal governor 57of a conventional type having a speed setting shaft 58 rotatable thereinwith a lever arm 59 secured thereto. The speed setting shaft 58 isadapted upon rotation in a counterclockwise direction to increase thegovernor speed setting and conditions the governor to regulate the fuelsupplied to the engine to maintain engine speed and power output in awell known manner in accordance with the speed setting establishedthereby. As shown, the speed shaft and the lever 59 are in their engineidle speed maintaining position. The end of the lever 59 distal from theshaft 58 is pivotally connected to one endof a link 60. The opposite endof the link 60 is pivotally connected intermediate the ends of an outputlever 61 of a pressure operated motor or actuator device 62.

The actuator unit 62 is connected to one end of a pressure supply pipe126 and is operable in accordance .4 with pressure supplied thereto toadjustl the speed setting of the governor. Variations in the pressuresupplied to the actuator unit above a predetermined minimum eect theieciprocation of a rod or plunger element 64 which is pivotallyconnected to the actuator output lever intermediate its connection tothe link 60 and a stationary pivot 63 at one end of the output lever.Thus an increase in the pressure supplied to the actuator effectscounterclockwise speed-increasing movement of the lever 61 about itsstationary pivot 63. The pressure responsive move-V ment of the actuatorlever 61 is limited between engine idle and maximum speed and loadpositions defined by stop screws 65 and 65', respectively. The governorspeed adjusting linkage intermediate the governor and the spedeadjusting actuator is biased in a fuel decreasing direction inopposition to the pressure applied to the actuator unit by suitablespring means, not shown, associated with either the governor or thespeed adjusting actuator.

DESCRIPTION-FIGURE l1 In the form of the invention shown in Figure 1,two control stands 66 and 67 are provided for controlling the operationof the two-way reverse clutch and the speed setting of the enginegovernor. For the purpose of illustration, the control stand 66 isdesignated as a pilot house control station and the control stand 67 isdesignated as an engine room control station. As the two control standsare identical in structure and function, corresponding elements of thetwo stands are hereinafter designated by the same reference numeral, theelements of the engine room stand being differentiated only by the useof a prime The selection of the controlling station is accomplished bythe selective operation of a transfer valve 68 including a valve member68' shiftable between either of two. control positions in which thetransfer valve is effective to connect the selected control station to amain pressure supply pipe69 and to deliver pressure control signalstherefrom to other elements of the overall control system. The transfervalve member 68 may be selectively shifted between. its two controlpositions by any suitable manual control means, not shown, from alocation adjacent either control station. In the position shown, apassage or port a provided in the transfer valve member 68 connects themain pressure supply pipe 69 to pipe 70 for supplying pressure fluidtothe several control elements of the control stand 66 thus renderingthe stand 66 effective to control the operation of the reverse clutchmechanism and of the governor speed adjusting actuator.

A single manually operable maneuvering control lever 71 is secured to acontrol shaft 72 which is rotatably` mounted in the control stand 66 formovement between a neutral position or zone and full speed ahead andastern controlling positions to either side of the neutral position,such positions of the control lever being designated by suitable legendsin Figure 1. Two cams 73 and 74 are carried by the shaft 72 andselectively actuate an ahead shift control valve 75, an astern shiftcontrol valve 76, and a variable pressure regulator valve 77 inaccordance with the direction and degree of movement of the controllever 71 from its neutral Zone.

The cam 73 is engaged by two diametrically opposed cam-following valvemembers 78 and 79 of the two shift control valves 75 and 76. The valvemembers 78 and 79 normally engage a base circle on the cam 73 when thecontrol lever 71 is in its neutral zone. When in such engagement withthe base circle, the valve members 78 and 79 are operative to connectboth an ahead shift control pipe 80 and an astern shift control pipe 81to an exhaust header 82. Operation of the control lever 71 beyond itsneutral zone in either-direction causes a single lobe A formed on thecam 73 to shift either the valve member 78 or 79, in accordance with thedirection of lever movement, to connect either the ahead or astern 54Shift control pipe 80 or 8,1, respectively, to the pressure supply pipeThe valve member 78 or 79 not shifted by the cam lobe upon such levermovementcontinues to engage the base circle of the cam 73 and thuscontinues to exhaust the shift control pipe associated therewith.

The variable pressure regulator valve 77 includes a valve member 83which is adapted` to follow the cam 74. The contour of the cam member 74is such that when the control lever 71 is in its neutral zone the valvemember 83 is operable to connect a clutch inflation and speed controlpipe 84, to the exhaust header 82 of the control stand. Movement of thecontrol lever through the indicated end of its neutral zonein an aheaddirection causes a lobe B on the cam 74 to actuate the valve member 83to a control position in which it is eiective to deliver an initialpressure signal to the pipe 84 which, it applied to the ahead clutchwould be suilicient to equal the biasing action of the springs 44.Further movement of the control lever 71 in the ahead direction betweenits neutral zone and an intermediate lever position, designated idle inFigure l, causes the cam operated valve member S3 to progressivelyincrease the `pressure signal supplied to the pipe 34 up to a pressurewhich, if applied to the ahead clutch actuating tube 40, would normallybe eiective to provide full lookup engagement at engine idle speed andload conditions. The lobe B `of cam 74 is so contoured that furthermovement of the control lever 71 through its idle position increases thepressure signal delivered to the pipe 84 by the pressure regulator valveto a value which, if applied to the engine governor speed adjustingactuator 62, would equal the biasing action of the spring meansassociated with the speed adjusting linkage intermediate the governorand actuator. Still further movement of the control lever betweenitsidle and full ahead positions is effective to progressively increasethe pressure signal supplied to the pipe 84 to a maximum pressure which,if applied directly to the ahead clutch and engine speed actuator, wouldprovide for maximum clutch running torque capacity and maximum enginespeed. Movement of the control lever 71 between its neutral zone and itsfull astern position causes a second lobe C on the cam '74 to actuatethe valve member 83 to supply corresponding pressure signals to thespeed and clutch inflation control pipe 84.

In addition to the pressure supply passage a, the transfer valve member68' is provided with passages b and c which, in the position shown,interconnect the pipes and 81, respectively, to pipes 85 and S6,respectively.

The pipes 85 and S6 are connected to opposite ends of a double-actingfluid motor 87 which is operable to control the operative position of afour-Way shift selector valve 88. The pipes 85 and 86 are preferablyeach provided with a conventional flow control type valve indicateddiagrammatically at 8S' and 86', respectively, consisting of an orificerestricting uid flow toward the motor 87 and permitting relativelyunrestricted ow away from the motor. The transfer valve member 68 isalso provided with a passage d which, in the position shown,interconnects the speed and inflation control pipe 84 to a pipe S9. Thepipe 89 leads to a pilot operated pressure regulating relay valve 90.The pressure regulating valve 90 is adapted to interconnect a speed andinflation control pipe 91 to either the main pressure supply pipe 69 oran engine room exhaust header 92 and supplies an output pressure to thespeed and ination control pipe 91 equal to the pilot signal imposedthereon. Thus when the control lever V71 is in its neutral zone, whereinthe pressure regulator valve 77 is operable 'to -vent the pipe 84 toexhaust, the pressure regulating relay valve 90 is similarly operable toconnect the pipe 91 to the exhaust header 92. Upon movement `of thecontrol lever 71 from its neutral Azone in either direction, the pilotpressure imposed on the pressure regulating relay valve 90 causes theregulating relay 90 to supply the same pres sure to the speed andination control pipe 91 from the main pressure supply.

The four-way selector valve 88 comprises a cylindrical housing or barrel93 having a bore 94 extending axially therethrough. A valve member 95 isreciprocably mounted'within the bore 94 by a plurality of axially spacedO-ring seals 96 which are compressively interposed between and retainedwithin the bore 94 by a plurality of annular port defining rings 97. Aninlet port 98 opens on the bore 94 intermediate its ends and isconnected to the speed and ination control line 91. Two outlet ports 99and 100 open on the bore 94 in flanking relation to the inlet port 98.These outlet ports are connected to an ahead inflation control pipe 101and an asterninflation control pipe 102, respectively, which are in turnconnected to the annular ports 54 and 55, respectively, of the annularrotary seal member 56. The valve barrel 93 is further provided with twoexhaust ports 193 and 104 which open on the bore 94 and are spacedaxially outwardly of the outlet ports 99 and 100, respectively. Theseexhaust ports are connected to the engine room exhaust header 92.

The valve member 93 is provided with two axially spaced reduced diameterlands 105 and 106 which separate enlarged diameter land portions 107,108 and 109 adapted to sealingly engage the port separating O-ring seals96. A piston member 110 carried by the valve member 95 is reciprocablymounted within the cylinder S7 and defines two double acting expansible4chambers 111 and 112 therein which `are connected to shift controlpipes 85 and 86. The valve member 95 is thus shiftable to an extremeleft-hand position in response to fluid pressure applied to theexpansible chamber 111 of the cylinder 87 through the shift controlpipes Sii and 85, the chamber 112 being simultaneously vented to exhaustthrough pipes S1, 86 and the astern shift control valve 76. In thisleft-hand position the reduced diameter land 105 interconnects thepressure inlet port with the ahead ination outlet port 99 and the asterninflation tube is connected to exhaust by the reduced diameter land 106.Similarly, a shift controlling pressure signal applied to the expansiblechamber 112, chamber 111 being vented to exhaust, is operable to shiftthe valve member to an extreme right-hand position wherein the reduceddiameter land 105 serves to vent the ahead clutch and the reduceddiameter land 106 interconnects the astern clutch inflation tube to thepressure inlet 98.

When the control lever 71 is in its neutral position, it will be notedthat both the expansible chambers 111 and 112 will be vented to theexhaust header 82 through the shift control valve 75 and 76. When thechambers 111 and 112 are thus vented, the Valve member 95 is adapted tobe centered to the position shown in Figure l by a centering springassembly 113 mounted on the end of the valve barrel 93 opposite theactuator cylinder 87. ln this intermediate position, the lands 105 and106 connect both the ahead and astern inflation pipes 101 and 102 to theexhaust ports 103 and 104, respectively. The centering spring assemblyincludes a cylindrical casing 114 having two inwardly extending, axiallyspaced an nular shoulders 115 and 116. The shoulder 116 is in the formof a groove-mounted snap ring. rl`he shoulders 115 and 116 serve asabutment stops for two Washer members 117 and 118 which slidably embracea reduced diameter land formed between two axially spaced shoulders 120and 121 carried by the adjacent end of the valve member. A spring 122 iscompressibly interposed between the washer members 117 and 118 andserves to center the valve member by axially aligning the abutmentshoulders 115, 120 and 116, 121 of the casing 114 and valve member 95,respectively, in the absence of actuating pressure in either of theexpansible chambers 111 and 112.

-In the `form of the invention shown in Figures l and la, the speedcontrol pipe 126 is provided with a ow f t :warmesvvv control valve 126diagrammatically shown to be of the type having an orifice` limiting theflow of actuating fluid to the `speed actuator 62'and a check valvepermitting unrestricted flow therefrom. The speed control pipe 126 isalternately connectable through a two-way lcheck valve 123 to either theinflation pressure supply pipe 101 or 102.v The two-way check V Valve123 comprises a cylindrical casing closedat both ends and reciprocablymounting a check valve member 125. Two branch, pipes 101 and 102 connectthe clutch inflation pipes 101 and 102, respectively, to opposite endsof a check valve casing and the pipe 126is connected theretointermediate its ends. The valve member 125 is shiftable in response tothe pressure supplied to either of the pipes 101 or 102, the other linebeing vented to exhaust, to permit the flow of the supplied pressurizedfluid to the speed adjusting actuator 62.

DESCRIPTION-FGURES 2 4 Operations of embodiment of Figures I and la Theoperating characteristics of the form of the invention of Figures 1 andla are best shown by the several graphs of'MFigures 2, 3 and 4 havingreference to a specific application thereof to a tug having a dieselengine prime mover rated at 1000 S.H.P at 750 r.p.rn.

InFigure 2, curve I indicates the interrelationship between thepropeller speed, in direct proportion to the engine speed, and thepressure signal supplied to the inflation and speed control pipe 84 bythe control stand pressure regulator 77 upon movement of the controllever between its neutral and either its full ahead or astern positions.Curve II represents the minimum clutch inflation pressure required tomaintain a given output shaft speed when the tug is running free,without tow, and thus represents a minimum torque condition. Curve Illrepresents the minimum clutch inflation pressure required to maintain agiven output shaft speed when the tug is driving against a dock thussimulating a torque condition corresponding to that required to initiatea tow. Above the clutch slip range curves II and Ill further define theinflation pressures at which the speed of the output shaft of the clutchcorresponds to that of the clutch input shaft, the creep therebetweenbeing less than one revolution for thirty minutes of operation. Asindicated, the pressure differential between curves l and Il or IIIrepresents additional available clutch torque capacity for accelerationof the tug and its tow. This excess torque capacity insures against anyprolonged periods of clutch slippage under high speed and torqueconditions. f

Assuming the engine to be operating at idle speed with the control lever71 of the controlling station in its neutral position or zone, both theahead and the astern clutches are de-energized since the shift selectorvalve member 95 is in its neutral position venting both inflation tubes40 and 41 and the governor speed setting actuator 62 to exhaust. Initialmovement of the control lever from its neutral Zone actuates one of theshift control valves 75 or 76 to supply actuating pressure to one end ofthe actuating cylinder 87 thereby causing the piston 110 to shift theselector valve member 95 to one of its two shift controlling positionsin accordance with the direction of control lever movement. Such initialmovement of the control lever also shifts the regulating valve member 83to close the connection between the exhaust header 82 and the inflationand speed control pipe E4 and to provide an'initial supply ofpressurized fluid of approximately three pounds per square inch to thelatter pipe. As duplicated by the pressure regulating relay valve 90 andsupplied to either of the clutch actuating tubes 40 or 41 through theshifted selector valve 8S, this initial pressure of three poundsissufficient to overcome the biasing action of the springs 44 andinitiates frictional driving engagement between the several plates ofthe corresponding clutch unit thereby initiating rotation of thepropellerl shaft. Further advancement of the control lever 71 in eitherits ahead or astern control slip ranges serves toincrease the actuatingpressure supplied to the oncoming clutch thereby decreasing the slip andincreasing the torque transmitted between the driving and drivenmembers. Thus the speed of the propeller shaft may be effectivelycontrolled by the operator-selected position of the control lever tohold the tug against a tidal or river current or to slowly and smoothlyinitiate propulsion of the tug and its tow. The actuating pressuresupplied to the oncoming clutch will generally be effective to shift thetwo-way check valve 123 to supply such pressure to the speed controlvpipe 126. However, when the control lever is in either of its clutchslip zones, such supplied pressure will be ineffective to actuate anadjustment of the governor speed setting. Y

As the control 71 is advanced toward its idleV position,

the inflation pressure supplied by the regulator valve 77 approaches avalue of approximately 10 pounds per square inch which is the inflationpressure required to" provide full engagement between the driving anddriven members of the clutch unit under engine idle maximum torqueconditions. Further movementof the( control lever into its vengine idleposition causes the regulator valve 77 to increase the pressure suppliedto the inflation and speed control line 84 to a value of approximately121/2 p.s.i. When duplicated by the relay regulating valve and suppliedthrough the shifted selector valve to either of the inflation controllines 101 or 102 and therefrom through the two-way check valve 123 tothe speed control line 126, this pressure is effective to counterbalancethe spring means biasing the governor speed adjusting linkage to itsidle position. Movement of the control lever between its idle and fullspeed ahead or astern positions varies the magnitude of the pressuresignal supplied to the line 84 by the regulator 77 in proportion to thedegree of movement of the control lever. Thus, for any given position ofthe control lever in either of its idle-to-full speed zones, a pressuresignal is provided which provides a given torque capacity for thedriving coupling and effectsA the adjustment of the governor speedsetting to provide a given engine speed and thereby a given propellershaft speed.

In actual practice, the operation of the control lever 71 will generallynot be accomplished slowly and smoothly enough to increase the pressuresignal and thereby prof peller speed as per curve I of Figure 2.

Normally the operator will actuate the control 71 almost instantaneouslyto a position corresponding to the desired propeller shaft speed.Assuming an almost instantaneous movement of the control lever 71 fromits neutral control zone to a second position within its ahead enginespeed controlling zone, such a movement of the lever causes the aheadshift control valve 75 to supply a pilot signal to the cylinder 87thereby actuating the valve member to its ahead drive establishingposition. Such lever movement also rapidly actuates the regulatorV valvemember 83 to a position wherein it is effective to supply a pilotpressure signal corresponding to the second position ofthe lever 71, byway of example, 50 pounds per square inch. This pressure signal isapplied to and duplicated by the pilot operated pressure regulatingrelay valve 90. The flow of the 'pressurized fluid emanating from theregulating relay valve 90 through the selector valve 88 to the aheadclutch actuating tube 40 and through the two-way check valve 123 to thegovernor speed actuator 62 is retarded or throttled by the orice of theow control check valve 91'. The flow of the supplied actuating pressureto the governor lspeed actuator 62 is further retarded by the flowcontrol valve 126'. It will thus be seen that the flow controlvalve 91'controls the ination of the clutches to provide relatively smoothprogressive engagement under such Aoperating conditions and'cooper-lates with the ow control valve 126 to retard advancerrr-entf of' theengine speedg governor` setting. during clutch t.

achieve'` a reversal of: propeller drive from full speed ahead to fullspeed astern, or vice versa,` within a period of ve seconds withoutundue; heating andV wear of the several clutch elements. In Figure 3curve IV represents enginespeed per unit time and: curve VIE representsthe speed andi direction of the propeller shaft` per unit time dringfsuch a high. speed` reversal. Curves V and` VII indicate correspondingengine and propeller speed` curves andthe minimum. time for effectingsucha high speed reversal with a comparable electric drive for` the sametug. In Figure 4 the engine speed curve IV is duplicated during/the fullspeed astern to full speed ahead reversal ofthe propeller shaft, thespeed of which is indicated by thecurveVIII.. The broken line curve IXin this figure indicates the free wheeling of the propeller shaft whichwould occur upon complete disengagement of the astern driving clutch12if engagement of the ahead clutch were not, almost immediately initiatedto eiect a braking action ontheastern rotation of the propeller driveshaft system.

The. operation ofthe control system during such high speedi maneuveringreversals is outlined briefly below. Movement of. the control lever 71from its full ahead position to `its full astern position vents thevalve shift actuator` chamber 111 through the ahead shift control valve75 to the exhaust header 82. Opening of the check valve of theow controlvalve assembly 85' permits this venting of the chamber 111 to berelatively unrestricted. However, the pilot pressure from the asternshift control valve` 76 is restricted in its applicationto theexpansible chamber 112 by the orifice of the flow control valve 86.

Consequently, the centeringV spring assembly 113 initially actuates thevalve member to its centered position, wherein it vents the ahead clutchand the governor speed adjusting actuator to the exhaust header 92,until the astern shift pilot pressure is sufficient in the expansiblechamber 112 to shift thevalve member 95 to its astern. shift controllingposition `wherein the land 106 interconnects the astern inilationandspeed control pipe 102 to the regulated pressure supply of the relayvalve 90. During the rapidI movement of the control lever 71 from itsfull ahead 'to-full astern positions the ination and speed controllingpilot signal emanating from the pressure regulator valve. 77 is reduceduntil the control lever passes through its neutral zone wherein theination and speed control pilot line 84 are connected to the exhaustheader S2 and is subsequently increased until it again reaches its fullengine speed value. However, it should be noted that this pilot inationand speed controlling signal, as duplicated byv the relay valve 90, isnot applied to the oncoming astern clutch until the initial centering ofthe shift selector valve 95 has first vented the ahead clutch inationtube and the governor speed actuator thereby substantially disengagingthe ahead clutch and reducing the engine governor to its idle speedsetting. This is best seen from curves VI, VIII and IX which show thepropeller shaft speed curves VI and VIII tending to follow the freewheeling curve IX until the engine speed has been reduced substantiallyto its idle position.

By proper selection or adjustment of the orifice size of the ow controlvalve assembly 86', as the engine appraches `its idle speed the shiftselector valve member Figures;L 3 t and 4, it is` V is` shifted; to; itsasternw .controlling` position` thereby,-

initiating the il'owrofactuating pressure tothe oncoming` asternwclntch.This flow 0f pressurized fluid" tothe on.- coming` clutchiswof courserestricted by the-How control valve assembly/w1 Hence, the astern clutchissmoothly and progressively. energized` throughout its clutchv sliprangel to initially,` brake the` ahead rotation of the propeller shaft;system` down to zero speed and then to` reverse and drive the propellerwith increasing speed and torque. As the` astern clutch becomeseffectively fully engaged at engine-idle speed, the increasing pressureis applied to,` thegovernor. speed actuator through thetwowaychecktvalve 12,3 and serves to progressively increasev thegovernor speed setting, up to its full speed and` power` maintainingposition.

A reversal. from. full` speed astern to full speed aheadis similarlyeffected-by the embodiment of the invention; of Figures 1f and. la, asshown by the graph of Figure 4, and consequently need not be discussedin detail. However, it.- willybe noted` that the propeller shaft andengineKV speed curves `IV--and VIIIf coincide between the point at whichthe oncoming aheadY clutch` is fully engaged and the full` speed aheadcondition.

From' the f oregoingdescription ofthe operation of the form of theinvention of Figures 1 and 1a it will be` seen that the four-way-shiftselector valve 88 provides a positive mechanical interlock preventingthe simultaneous, supply ofV actuating. pressure to the actuating tubesof` both the ahead and astern` clutches and when utilized with the owcontrol valves S5 and 86 insures substantial disengagement of theoifgo'ing clutch before engage,- ment ofthe oncoming clutch isinitiated. This latter feature, when., taken in conjunction. with thetwo-Way check valve 123, Aserves to provide a positive pneumaticinterlock between, clutch inflation. and engine speed and` is effectiveto-reduce engine speed` during` reverse maneuvering operations therebyprevent-ing excessive heating of` the clutches. Thisinterlockingarrangement also prevents stalling o'r overloading theengine during such reversing operations since theclutch torque capacityat any particular pressure setting within the clutch-slip, engine idleVrange is insuflicientto stall the idling engine. After initial fullclutch engagement, the available clutch torque` capacity at anyparticular pressure setting is: substantially greater than the availableengine torque. It should also`V be notedl that since clutch inationpressure is used to control the governor actuator through the two-waycheck valve, this arrangement will automatically result in a reductionin engine speed in the event of a low clutch inflation pressure whichmight otherwise permit destructive clutch slippage.

DESCRIPTION-FIGURE 5 In the form of the invention of Figure 5, the driveintermediatethe engine and the propeller shaft, the engine governorspeed adjusting mechanism, and the remote control stations, as well as`other component elements, are identical with those shown and describedwith reference to Figures 1 and la. Such components are thereforerepresented by the` same reference numerals in Figure 5 although beingshown somewhat more diagrammatically.

In this form of the invention, the pilot pressure actuation of thefour-way selector valve 88 by the control lever operation of the shiftcontrol valves 75 and 76 is positively interlocked by means of suitableclutch inflation pressure actuated relays 134)y and 131 to assurecomplete disengagement of one clutch before the other clutch is actuatedto drivingly connect the propeller shaft to the engine. This positiveinterlocking o'f the` selector valve `shifting is utilized in place ofthe controlled time delay which is introduced by the ow control valves85 and 86' of the first embodiment and momentarily maintains theselector valve in its neutral position during the reversal cycle.

The inflation pressure actuated relays and 131 are associated with andadapted to control the tlow of pres.-

surized fluid to the opposite ends of the shift selector valve actuatingcylinder 87 through the pipes 85 and 86, respectively. The valve membersof these twov relays are normally spring biased to a position indicatedby the broken lines e and f, respectively, to provide a through passagebetween the separate ends o'f the pipes 85 and 86, respectively. -Toassure complete disengagement of either the ahead or astern drivingclutch before the other clutch is energized to pick up torque, thepressure actuating means of the ahead shift controlling relay 130 isconnected to the astern speed and inaton control pipe 102` by a pipe102' and the pressure actuating means of the astern shift control relay131 is similarly connected to the ahead ination and speed control pipe101 by the pipe 101'. Hence, when an inflation and speed control- /lingpressure is supplied to the pipe 101 sufficient to initiate engagementof the ahead clutch, this signal is applied to the astern shift controlrelay 131 and is operative to actuate the valve member thereof to asecond co'ntrol position indicated by the broken line f to connect theportionof the pipe 86 intermediate the actuator cylinder 87 and therelay to the engine room exhaust header 92. An engagement initiatinginilation pressure supplied to the pipe 102 is similarly effective onthe ahead shift controlling relay to connect the expansible chamber 111of the shift actuator 87 to the exhaust header 92 as indicated by thebroken line e. Thus when the control lever is reversed as in fastmaneuvering, shifting of the selectorl valve to effect a reversal isprevented until the pressure in the engaged clutch is reduced toapproximately its minimum inflation pressure.

It should be noted that the interlocking rclay'valves 130 and 131 delaypressure supply to the oncoming clutch in proportion to the oppositeclutch ination pressure, but only during reverse maneuvering operation.Direct response is still attainable whenever the control lever 71 ismoved from its neutral position, with both clutches disengaged, toeither an ahead or an astern drive controlling position.

To' compensate for the somewhat delayed energization of the oncomingclutch during rapid maneuvering operation of this system, relative tothat provided by the first form o'f the invention, a relay valve 135 isprovided which is operative to control a passage or pipe 136 bypassingthe flow contro'l valve 91'. Whenever the pressure in the portion of thepipe 91 between the flow control valve 91' and the selector valve isabove the minimum pressure required for full clutch engagement, thispressure is applied to the relay valve 135 by branch pipe 136 and isoperative to shift the relay valve Ymember between a closed position,indicated by the broken lines at g', to an o'pen'bypassing position,indicated at g. This permits a rapid and relatively unrestrictedbuild-up of the inflation pressure applied to the oncoming clutch and tothe governor speed adjusting actuator through the pipe 126 and the flowcontrol valve 126' and thus provides for a more rapid advance of theengine governo'r speed setting shaft between its idle and maximum speedand load positions.

As a further refinement of the form of the invention shown in Figure 5,two ow control valves 132 and 133 are interposed in the pipes 102" and101, respectively. Such valves introduce a time delay in the build-up ofinterlocking pressures applied to the relay valves 130 and 131,respectively, while permitting relatively unrestricted venting of suchinterlocking pressures from the relay valves. By properly proportioningthe orifices of such ow co'ntrol valves, immediate response or shiftingof the selector valve is permitted Without interlocking when the controllever is rapidly actuated between its idle ahead and idle asternpositions.

DESCRIPTION-FIGURE 6 In the embodiment of the invention shown in Figure6, a control lever 140 of a pilot house control stand 141 is operativelyconnected to a rotary' actuator device 144 by z suitable hydraulic,electrical or mechanical means inditrol stands 66 and 67 of thepreceding embodiments. The control shaft 146 is also adapted to bemanually operated by a control lever 148 mounted thereon.

The control stand 147 is connected to a suitable source of pressurizeduid by a pipe 149 and is adapted upon movement of either control leveror 148 in an ahead direction to deliver an ahead-shift pilot signal to apipe..

150 or upon movement of either control lever in an astern direction todeliver an astern shift pilot signal to a pipe i The control stand 147is also adapted to deliver` 151. a variable inflation and speedcontrolling pressure signal to a pipe 152, such signal beingproportional to the angular movement of either control lever from itsneutral` position.

A ow control valve 153 interposed in the pipe` 152 corresponds to the owcontrol valves 91' of the preceding embodiments. T he pipe 152 isconnected by two branch pipes 154 and 155 to the inlet ports of twopressure operated, three-way relay valves 156 and 157, respectively,which serve as ahead and astern shift control valves replacing thesingle four-way, spring cen-` tered and pressure actuated shift valve 88of the preceding forms of the invention.l The relay valves 156 and,

157 are of conventional design and have valve members which are normallyspring biased to provide exhaust connections m and n', respectively,between the clutch inflation and speed control pipes 101 and 102,respectively, and the engine room exhaust -headerv92. Each relay valvemember is shiftable to a second operative position in response to ashift controlling pilot signal applied thereto wherein pressuresupplying connections m and n are established between the pipes 154 and101 and between the pipes and 102, respectively.

The application of the shift controlling pilot signals from the pipes150 and 151 to the shift control relay valves 156 and 157, respectively,is controlled by the interlocking action of two inflation pressureactuated relay valves 158 and 159 corresponding to the interlockingrelays 130 and 131 of the embodiment of Figure 5. The valve members ofthe interlocking relay valves 158 and 159 are normally spring biased toa first position to provide through passages indicated o and p,respectively, between the ahead shift signal pipe 150 and a pipe 150'leading to the pressure sensing unit of the shift control relay valve156 and between the astern shift pipe 151 and a pipe 151 leading to thepressure sensing unit of the astern shift control relay valve 157,.

respectively. The valve member of the interlocking rclay valve 158 isshiftable to a second operative position o venting the pipe 150' to theexhaust header 92 in response to astern inflation pressure appliedthereto from. the pipes 102 and 102 through a pipe 102". The valvemember of the interlocking relay valve 159 is similarly shiftable to asecond position venting the pipe 151 to exhaust whenever ahead inflationpressure is suppliedk thereto from the pipes 101 and 101 through aninterconnecting pipe 101".

With the exception of the independent operation of the shift controllingrelay valves 156 and 157 and the omission of the flow control valves 132and 133` and the flow control bypassing relay valve 135, the operationof the embodiment of Figure 6 is essentially the same as that of theform of -the invention of Figure 5.

DESCRIPTION- FIGURE `7 It will be noted that with the embodiments oftheinvention of Figures l and 1a, 5, and 6, when the coni-i 'j trol leveris moved .fronr or through itsV neutral position, there will necessarilybe a lag period as the` pressure applied to the oncoming clutch buildsup to overcome the action of the spring` 44; before clutch engagement isinitiated to pick up the propeller load and start accelerating themasses involved in the propeller. drive system. Since the ow ofinflation pressure to the oncoming clutch through the tiow controlvalves 91' or 153 is proportional to the pressure supplied, such a lagwill be proportionally much` longer when the movement of the controllever is limited to a relatively low speed position. Such a lag may beovercome by the operator moving the control handle to a speed positionbeyond the speed at which he desires to operate with subsequent returnof the handle to its desired position. Such operation provides amomentary boost in the initial inflation pressure applied through the owcontrol valve to the oncoming clutch thus shortening the delay ininitial clutch engagement. Such a momentary pressure boost may also beprovided automatically with` the supplementary control mechanism shownin Figure 7.

The supplementary control of Figure 7, comprises a pressure operatedrelay valve 164 which is operable to control the flow of the inflationand speed controlling pressure signal either in the remote control pipe89 or in the engine room pipe 91 or 152 of the several precedingembodiments. The relay valve 164 has a valve member which isA normallyshiftable by the shiftcontrolling pilot signal from either the ahead orastern shift control pipe 85 or 86, respectively, to provide a throughconnection q, between the ends of the pipe 89 separated thereby. Theahead and astern shift signal supplying pipes 85 and 86 are connected tothe opposite ends of a two-way or double check valve 160, similar to123, through branch passages 85 and 86, respectively. The valve memberof the check valve 160 is shiftable, in response to the oncoming shiftcontrolling signal in one pipe and to the venting of the other, tosupply the oncoming shift controlling signal to a pipe 161 connected tothe check valve 160 intermediate its ends. The pipe 161 is connectedthrough a flow control valve 161 to the pressure sensing end of therelay valve 164 and to a chamber 165 of a predetermined volume. When thepressure applied to the pressure sensing end of the relay valve dropsbelow a predetermined amount, e.g. 40 p.s.i., the valve member thereofis adapted to be shifted to a second position q' connecting the outletend of the pipe 89 to a pipe 162. The pipe 162 is in turn connected tothe pipe 161 by a pressure regulator valve 163. The regulator valve 163is adapted to convert the shift controlling signal, e.g. 60 p.s.i., to apredetermined constant pressure, e.g. 30 p.s.i., and to supply suchconstant pressure to the pipe 162.

The operation of the supplementary control of Figure 7 is as follows,assuming the control stand lever to be actuated from an ahead drivingposition to an astern driving position. As the control lever passesthrough its neutral position, the ahead shift control pipe 85 is ventedto exhaust through the ahead shift control valve 75. This venting of theline 85 also vents` the pipes 85" and 161, the relay valve 164, and thechamber 165 to exhaust prior to the shifting of the two-way check valve33.60 in response to the build-up of the astern shift pilot signalsupplied thereto above the venting pressure in the ahead shift pipe.This effects a momentary reduction in the pressure applied to thesensing unit of the relay valve 164 and within the chamber 165 below 40p.si. Consequently, the valve member of the relay 164 is shifted to itssecond control position wherein the pipe 162 is connected to the outletend of the pipe 89 thus supplying the constant 30 p.s.i. pressure fromthe pressure regulator valve 163 to the inflation tube of the oncomingastern clutch. Normal ination and speed control is restored by the relayvalve 164` whenever the pressure in the pipe 161 intermediate the owcontrol valve 161' and. thel chamber 165agan` exceeds 40 p.s.i.` Thetiming for effecting such restoration of normal inflation and speed'controlA is accomplished by properly relating the volume of the chamberto the size of the orice of the ow control valve 161.

DESCRIPTION-FIGURE 8 The' form of the invention shown in Figure 8 isparticularly` adapted for use in those applications requiring highdegrees of control and responsiveness such as with multi-engineinstallations having a single output shaft.

The drive intermediate the engine and propeller shaft is identical withthat shown in Figure la, the ahead and astern clutch units respectivelybeing adapted to reverse the driving relation between the engine drivenshaft 20 and the input driving shaft 36` of the reverse gear unit 18. Asin the embodiments of Figures 1 and 5, the selective energizing anddeenergizing of the astern and ahead clutch units are controlled by theoperation of a four-way pilotoperated shift valve 88 which is shiftableto either of two shift controlling positions in response to theselective application of shift controlling pressure signals delivered tothe ends of the valve actuating cylinder 87 associated therewith or to acentered neutral position provided by the spring centering assembly 113.

This control system features the coordination of clutch engagement withthe propeller shaft speed during operation in the clutch slip speedranges to provide a relatively fast rate of response during reversalsfrom one slip range to the other. For operation above the clutch slipspeed ranges this control system is adapted to apply a single highpressure to thev inflation tube of the selected clutch which issufficient to` maintain full clutch engagement under all engine load andspeed conditions between idle andI full speed ahead or astern.Consequently, the speed controlling signal is necessarily regulated andsupplied to the governor speed adjusting actuator separately, althoughcoordinated with, the clutch inflation controlling signal. This requiresthe elimination of the speed controlling two-way check valve connectionintermediate the clutch inflation lines 101 and 102 andthe speedactuator of the preceding embodiments. It will be noted that thegovernor, the governor speed adjusting actuator and the interconnectinglinkages are shown diagrammatically to be similar to those of the rstand second forms of the invention and are therefore designated by thesame reference numerals.

The pressure supply for the instant system includes an air receiver 201which is connectable through a checkvalve-controlled pipe 200 to asuitable air compressor. The receiver is connected to and supplies aconstant actuating pressure to the propulsion control system through apipe 202, Vow through the pipe 202 being controlled by a combined filterand pressure regulator unit indicated at 202A and a manually operableshutoff valve 202B. A branch pipe 202 leading from the pressure supplypipe 202 is adapted to supply pressure through a flow control valve 244and a pressure operated relay valve 231 to a pipe 232 leading to thepressure inlet 98 ofthe four-way shift control valve 88 for clutchinflation during idle to full speed ahead or astern operation. A second`branch 202" from the pressure supply pipe 202 is controllable by theselective actuation of a valve member 203 of a transfer valve assembly203 to alternatively supply control pressure to either a pipe 204leading to a pilot house control stand 210 when the valve member is in.its position indicated by the broken lines at a or to a pipe 204 leadingto a similar engine room control stand, not shown, -when the valvemember is in its broken-line-indicated position a'.

As shown diagrammatically, the control stand 210 includes a manuallyoperable lever 211 which is secured to a control camshaft 212 rotatablymounted in the stand. The camshaft 212 is provided with four camsaxially spaced thereon and indicated at 213, 214, 215

and 216. The cam- 216 is yprovided with a first control lobe G which isadapted tov actuatc ,a valve member 205 of a shutoff valve 206 ,to aclosed position whenever the control lever 211 is within its neutralzone. Actuation of the control lever from its neutral zone permits thevalve member 205 to be shifted to a second position wherein the pressuresupply header 204d is connected to the pipe 204 through aninterconnecting branch pipe 204a thus supplying actuating pressure tothe several other control elements of the stand. A pressure operatedrelay valve 207 responsive to the pressure in the supply header 204d isadapted to provide a direct connection between the header 204d and thepressure supply pipe 204 through a branch pipe 204C whenever thepressure in the supply header 204d is in excess of a predeterminedpressure. With. this interlocking pressure supply arrangement, almomentary loss of control stand operating pressure, which wouldotherwise occur each time the control lever is actuated through itsneutral position, is prevented. It will be appreciated that this featureimproves the overall responsiveness of the system.

The cam 213 is similar in function and configuration to the cam 73 ofFigure 1, having a shift controlling lobe D thereon adapted toalternatively actuate the `valve member 218 of an ahead shift controlvalvev 217 to a position supplying a shift actuating pressure to theline 80 from the header 104d or to actuate the valve member 221 of anastern shift control valve 220 to a position supplying an astern shiftsignalwto the line 81 from the header 204d. When the ahead and theastern shift valve members are not in' actuating contact with the lobeD, as when the control `lever is in its neutral position, they arereturnable to a position interconnecting both of the shift control pipes80 and 81 to the'pilot house exhaust header 2719. As in the embodimentof Figure 1, the pipes 80 and 81 are connectable by the transfer valvemember 203', Whenin the positions indicated in broken lines at'c and b,to the pipes 85 and 86, respectively, which are connected to theopposite ends of the actuator cylinder 87 for shifting the fourwayvalve.

The cam 215 serves to control the slip engagement of the energizedclutch when the control lever 211 is actuated to a control positionWithin either of the indicated ahead or astern slip ranges. Theconfiguration of the cam 215 is such as to actuate la valve member 223of a` pressure regulator 222 to interconnect vthe pressure supply header204d to a pipe 224 `and to supply a variable pressure theretoproportional to the degree of movement of the control lever and of thevalve member 223 from their shown neutral positions wherein the valvemember 223 engages an arcuate surface of minimum radius on the cam 215and is adapted to connect the pipe 224 to the exhaust header 219. Thearcuate surface defining the neutral zone on` the camv 215 is flanked bytwo rises of increasing radius F and F Which are adapted topropressively shift the Valve member 223 to increase the regulatedpressure supplied lto the pipe 224 throughout the clutch slip ranges forahead and astern operation, respectively. The two cam rises F and Ftereminate in a cylindrical surface which extends therebetween on theside of the cam opposite the neutral zone and defines the maximumopening of the valve member 223 to provide the pressure required forfull clutch engagement under idle speed and load conditions. Theopposite end of the pipe 224 is connected to a pressure regulator relayvalve 225 of the so-called computing type'having an output pressurecontrolled in accordance with the differential between several pressurecontrol 4signals imposed thereon. The pressure `signal delivered by thepipe 224 to the relay valve 225. provides a first -control signal or setpoint for controllingthe pressure regulation thereof in accordance withthe desired speed of the output shaft. A second controlsignal orfsetpoint for the differential computing relay 225 is provided by and airtachometer 227 through an interconnecting pipe 22S. The tachometer 227is drivingly connected to the propeller shaft 16, as indicated at 226,and the pressure signal generated thereby is of course proportional tothe speed of the'propeller shaft.

' A pressure regulator valve 233 interposed-in a branch 204b of thepressure supply pipe 204 reduces the constant pressure supplied theretoto a lower constant output pressure equal to that pressure requiredl forfull clutch engagement under engine idle speed and load conditions andthis reduced pressure is supplied to the differential relay valve 225.As indicated above, the differential relay valve is adapted to regulatethe flow of fluid pressure from the branch 204b to an outlet pipe 229 inaccordance with the set point pressures imposed thereon. The pipe 229 isconnectable through an inilation pressure controlled safety relay valve230 and the inflation pressure supply controlling relay 231 to the inletpipe 232 of the four-way valve. The inflation pressure sensing unit ofthe safety relay valve 230 is connected to the pipe 232 by a branch pipe232". This safety relay valve insures the isolation of the relativelylow pressure differential relay valve 225 from the high inflationpressure which is supplied through the relay valve 231 under idle tofull speed ahead or astern operating conditions.

The operation of the differential relay 225 is such that a slip speedindicating signal of a given magnitude supplied to the pipe 224 when theoutput shaft 16 is at rest or rotating at a substantially lower speedcauses the relatively unrestricted flow of the pressurized fluidsupplied thereto to the energized or oncoming clutch. This imposes arelatively high initial or starting torque vcapacity on the oncomingclutch with resultant rapid acceleration of the output shaft 16.However, as the speed of the output shaft approaches the speed indicatedby the control stand regulated set point pressure in the pipe 224, theincreasing set point pressure supplied to the relay 225 by the airtachometer 227 causes the differential relay to reduce the pressuresupplied to the energized clutch by venting a portion of the pressurepreviously supplied to the pipe 229 to the exhaust header 92 until theinflation pressure required for the desired speed maintaining slippageis reached. Should the control stand set point pressure in the pipe 224be reduced to a pressure indicating a desired speed less than that ofthe output shaft, the computing relay will similarly vent a portion ofthe clutch inflation pressure to the exhaust header below that requiredfor the desired speed until the output shaft speed indicating set pointagain matches the set point pressure in the pipe 224.'

A second control stand mounted pressure regulator valve 234 is adaptedto supply a speed controlling pressure signal to a pipe 236 andtherefrom to the governor speed actuator 67 in accordance with themovement of the control lever 211 between its idle and full speed aheadand astern control positions; a pressure regulating valve member 235 ofthe regulator valve 234 being maintained in thrust engagement with thesurface of the cam 214 and actuated thereby. The surface of the cam 214is formed on a single radius intermediate its ahead and Vastern engineidle speed controlling positions and maintains the valve member 235 in aposition venting the outlet pipe 236 to the exhaust header 219throughout the neutral and slip range of movement of the cam 214 and thelever 211. At its engine idle speed controlling positions, the camsurface is provided with an initial rise adapted to actuate the valvemember 235 to an initial pressure supplying position wherein the minimumpressure required to counterbalance the engine idle maintaining means ofthe governor 57 and actuator 67 is supplied to the pipe 236. In itsidle-to-full speed ahead and astern controlling sectors the surfaces ofthe cam 214 are provided with rises as indicated at E and E',respectively, which are adapted to shift the valve member 23S to annalesT7 progressively increase the speed control pressure `signal supplied to`the pipe -236 nin Vaccordance with'the angular movement of the controllever in either speed increasing direction. o

The flow of the speed controlling pressure signal to the actuator 67through the pipe 236 is controlled by the orifice of a ow control type,check valve 237 and a pressure operated relay valve 23S. The relayvalve 238 `is operable to provide a through connection between the endsof the pipe 236 separated thereby in response to a predetermined.pressure signal supplied to the pressure sensing unit thereof. Intheabsence of such a predetermined pressure applied to its pressuresensing unit, -the relay valve 238 is Yadapted to vent the governorspeed actuator 67 to the engine room exhaust header 92.

The cam 216 is provided with a second lobe thereon diametricallyopposite end lobe G and` extends arcuately thereof through `an angularsector substantially equal to that subtended by the slip and neutralzones of the convrol lever. 4When the lever V211 is in its neutral oreither of its slip Zones, the lobe H thrustably `engages and actuates avalve member 239 of a shutoff valve 240 to a position wherein itprovides a connection between a pipe 2594s: and the control stationexhaust header 219. When the control lever 211 is shifted `to either ofits idle speed controlling positions, `the-lobe H no longer engages `thevalve member 239 which `is returnable to a position interconnecting thepressure supply header 2l4d to the pipe 204e.. The pressure thussupplied to the pipe 204e is delivered through branch pipes 204ftand204g connectedthereto' to the pressure sensing units of the inflationcontrolling relay r2,31 and 23S, respectively. The flow of pressurefluid to the relays through the branch pipes 204f and 204g liscontrolled by flow control valves 241 and ZAL-respectively, interposedtherein. By proper selection of orifice size for theflow control valves241 and 242 and the valve actuating pressures for the relays 231 and`238, the relay valve 231 will first be actuated to supply full inflationpressure to the engaged clutch prior to the actuation of the relayvalve238 to `supply speed increasing pressure to the governor speed actuator.

Operation of embodiment of Figure 8 The operation `.of the embodiment ofthe invention of Figure 8 will generally be apparent from the foregoingdescription. However, such `operation is outlined briefly below.

Assume the control lever is actuated from its neutral zone to an asternslip position. This initial movement of the control lever causes thevalve member 265 `to be shifted to its opened-position Supplyingpressureto the control stand supply header 26M. The astern shift valvemember 221 has similarly been shifted to its opened position and theshift controlling pressure signal thus supplied to the shift-valveactuator 87 causes that valve Vto be shifted to its astern controllingposition. The pressure signal supplied to the differential computingrelay V22S by the pressure regulatorvalve 222 in accordance with theadjusted position of the control lever and by the air tachometer 227inaccordance with the propeller speed causes the differential relay tosupply the idle speed full engagement inflation `pressure from thepressure regulator valve 233 tofthe astern clutch through the pipes 229,232 and 102 as controlled by the safety relay valve 230, the inflationcontrol valve 231 and the shift control valve it. As the speed of theoutput propeller shaft approaches the desired speed indicated by the`adjusted position of the control lever the differential relay valvereduces the astern clutch inflation pressure to provide the desiredpropeller `shaft speed.

If the `control lever`is now actuated to a position within its '.asternengine speed controlling sector, -the resultant'inorlease in thepressure signal in pipe 224 causesithecldifferential relay 225 toinitially supply the full output pressure ofthe pressure regulator 233to the 18 astern clutch. Since the flow of ,duid pressure to theinflation .controlling relay 231 and the speed controlling relay 238'isretarded by the flow control valves 241 and 242, respectively, thepressure supplied through the differential relay `initiates full asternclutch engagement prior to the actuation of the relay valve 231 toprovide full supply pressure to the engaged clutch and the subsequentactuation Vof the relay valve 238 to supply the speed controlling signalto the governor speed actuator.

In accomplishing a high speed reversal from the now established asternspeed to full speed ahead, the control lever is quickly actuated by theoperator to its full speed ahead position. The movement of the controllever 211 and the several cams through their astern slip ranges causesthe valve 24u to vent the pipe 204e to exhaust. This rapidlyexhauststhe'pressure sensing units of the relay valves 231 and 23Sthrough the ow control valves 241 `and 242 with the consequentialventing of the governor speed actuator to reduce the engine speed toidle and the re-establishing of the low pressure connection between thepipes 229 and 232.

As the several cams pass through their neutral positions and into theahead slip range the astern shift valve 220 vents the corresponding endof the shift valve actuator to exhaust to permit the oncoming shiftcontrolling signal provided by the valve 217 to actuate the #shift valveto its ahead `controlling position. As the control lever is-rapidlyadvanced to its full speed ahead position, the pressure signals imposedon the differential computing relay will be such as to initially applyidle speed engaging -pressure of the regulator valve 233 to the aheadclutch to eiect the engagement thereof prior tothefactuation .of therelay valve 231 to provide full supply pressure to the engaged `clutchand the subsequent actuation of the relay valve 238 to permit adjustmentof the `actuator- 67 to advance the governor to its maximum speed andload maintaining setting.

The preferred embodiments of the invention have been described in detailfor the purpose of explaining the several principles, objects,advantages and features of the invention and the bestknown means ofpracticing the invention. 1t is to be understood, however, that theinvention is not to be considered as limited by this description. Manymodifications may be made by the exercise of skill in the art withoutdeparting from the scope of the principles of the invention as definedin the following claims.

We claim:

l. A drive control apparatus including two couplings independentlyoperable by fluid under pressure to provide alternative drivingconnections between a load and a prime mover of torque capacitysubstantially proportional to the pressure of such fluid and operableupon release of such fluid under pressure to disconnect said load fromsaid prime mover, a power -control motor operable by fluid underpressure to adjust the speed of said prime mover between minimum andmaximum limits in proportion lto the pressure of such duid, a firstvalve means operable to selectively supply and release fluid underpressure to and from either one of said couplings, a second valve meansoperable to supply fluid under pressure to operate said motor, a controldevice operable to regulate the pressure of fluid supplied through saidfirst and second valve means to said couplings and motorand including acontrol element movable from a rio-pressure supply position to either oftwo full pressure supply positions, and means for controlling operationof said first and second valve meansto control the supply or" fiuidunder pressure .to and its release from each of said couplings and saidmotor in accordance with movement of said control element to and fromitsno-pressure supply position.

2. `An apparatus for controlling two couplings independentl-y operableby fluid under pressure to provide a driving connection between a loadand Va prime mover asada-e 19 of torque capacity substantiallyproportional to the pressure of such fluid and operable upon release ofsuch tiuid under pressure to disconnect said load from said prime moverand for also controlling a power control motor operable by fluid underpressure above a predetermined pressure to adjust the speed of saidprime mover in proportion to the pressure of such tiud, comprising incombination with said couplings and motor, a iirst valve means operableto selectively supply fluid under pressure to either one of saidcouplings and at the same time release fluid under pressure from theother coupling, a second valve means operable in response to the supplyof fluid under pressure to either one of said couplings'to provide aconnection between said one coupling and said motor to thereby supplysuch fluid under pressure to operate said motor, a control deviceoperable `to regulate. the pressure of uid supplied through said iirstand second valve means to said couplings and motor, said control deviceincluding a control element movable from a no-pressure supply positionto either of two full pressure supply positions and means forcontrolling operation of said first valve means to control the supply offluid under pressure to and its release from each of said couplings inaccordance with movement of said control element to and from itsno-pressure supply position.

3. A drive control system including two couplings each independentlyoperable by pressurized liuid to provide a driving connection between aload and a prime mover of torque capacity substantially proportional tothe effective pressure of such iluid and operable upon release, of suchpressurized uid to disconnect said load from said prime mover, a powercontrol motor operable by pressurized fluid to adjust the speed of saidprime mover in proportion to the pressure of such fluid, a

`control device operable to regulate fluid pressure for supply to saidcouplings and to said motor and including a control element movablebetween two maximum pressure s upply positions through a no-pressuresupply position, a rst valve means including a valve member shiftable toselectively supply pressurized uid from said control device to and torelease pressurized fluid from l either one of said couplings, a secondvalve means operable in response to a higher pressure of lluid in eitherone of said couplings to provide a connection between said power controlmotor and said one coupling whereby pressurized tiuid as supplied tosaid coupling is supplied to operate said motor, and means associatedwith said control device for shifting said valve member to control thesupply of fluid under pressure to and its release from each of saidcouplings in accordance with the movement of said control clement to andfrom its no-pressure supply position, said last-mentioned means beingoperable upon operation of said control device element to or through itsno-pressure supply position to shift said valve member to a positionwherein said member is adapted to simultaneously release tluid underpressure from both of said couplings and to delay further movement ofsaid valve member and thereby the supply of fluid under pressure to theother coupling to permit a reduction in the pressure of uid in said onecoupling below a chosen pressure. Y

4. A power plant drive control mechanism comprising,V in combination,two friction couplings independently operable by uid under pressure toprovide alternative driving connections between a load and a prime moverof torque capacity substantially proportional to the pressure of suchliuid and operable upon release of such fluid under pressure todisconnect said load from said-prime mover, a power control motoroperable by fluid above a predetermined pressure corresponding to thatrequired to establish initial full engagement of such couplings toadjust the speed of said prime mover-in proportion to the pressure ofsuch fluid between minimum and maximum limits, a first valve meansoperable to selectively supply and release uid Vunder pressure to andfrom said couplings, a second valve means operable in response to thesupply of fluid under pressure to either one of said couplings toprovide a connection between said one coupling and said motor to therebysupply such fluid under pressure to operate said motor, a' control`device operable to regulate the pressure of fluid supplied through saidtrst and second valve means to said couplings and motor and including acontrol element movable between `a no-pressure supply position andeither of two full pressure supply positions, means for controllingoperation of said first valve means to control the supply of fluid underpressure to and its release from each of said couplings and said motorin accordance with movement of said control element to and from itsno-pressure supply position and operable upon movement of said controlelement to or through its nopressure supplyposition to Vrelease `tiuidunder pressure from either 'one of said couplings and said motor, andmeans associated with said last-mentioned-means for delaying the supplyof uid under pressure to the other coupling until the pressureof fluidin said one coupling is reduced below a chosen pressure upon movement ofsaidcontrol element through its no-pressure supply position.

V5. VAn apparatus for controlling two couplings independently operableby fluid under pressure to provide a driving connection between a loadand a prime mover proportional to the pressure of such fluid andoperable upon release of such fluid under pressure to disconnect saidload from said prime mover and for also controlling a power controlmotor operable by iluid under pressure above a predetermined pressurevto adjust the speed of said prime mover in proportion to the pressureof such uid, comprising in combination with said couplings and motor, arst valve means operable to selectively supply uid under pressure to andits release from said couplings, a second valve means operable inresponse to the supply of fluid under pressure to either one of Vsaidcouplings to provide a connection between Vsaid one coupling and saidmotor to thereby supply such fluid under pressureto operate said motor,a control device operable to regulate the pressure of Huid suppliedthrough said iirst and second valve means to said couplings and motorand including a control element movable from a no-pressure supplyposition to either of two full pressure supply positions, and means forcontrolling operation of said rst valve means to control the sup-` plyof iluid under pressure to and its release from each of said couplingsin accordance with movement of said control clement to and from itsno-pressure supply p0- sition, said last-mentioned means including meansoperable upon movement of said control element to or through itsno-pressure supply position to permit relatively unrestricted actuationof said rst valve means to release fluid under pressure from one of saidcouplings and to delay further actuation of-said first valve means andthereby the supply of uid under pressure to the other coupling to permitthe pressure of uid in said one coupling to be reduced below a chosenpressure.

6. An apparatus for controlling two couplings independently operable bylluid under pressure to provide alternative driving connections betweena load and a prime mover of torque capacity substantially proportionalto the pressure of such fluid and operable upon release of` such fluidunder pressure to disconnect said load from said'prime moverl'and foralso controlling a' power controll motor operable by fluid underpressure above a predetermined pressure to adjust Vthe speed of saidprime mover in proportion tothe pressure of such fluid between minimumand maximum speed limits, comprising in combination with said couplingsand motor, afrst valve means operable toselectively` supply lluid underpressure to either one of said couplings and at the same time'releaseiluid under pressure from' the `'other coupling,` a secondV valve meansoperable in relsponse to the supply fofuid under pressure `to` either`one of said couplings to provide `a connection between `said onecoupling and said umotor to thereby supply such vfluid under pressurelto operate said motor, a control device operable to regulate thepressure of fluid supplied through said first and second valve means tosaid couplings and motor and including a control element movable from ano-pressure supply position to either of two full pressure supplypositions, means for controlling operation of saidiirst valve means tocontrol thefsupply of fluid under pressure to and its release from eachof said couplings in accordance with movement of said control element toand from its no-pressuretsupply position and operable upon movement ofsaid control element to or through its no-pressure supply position tocause said first valve4 means `to release fluid under pressure fromeither one of said couplings, and interlock means operable in responseto lthe pressure of fluid supplied to either one of said couplings todelay the supply of uid under pressure to the other coupling uponmovement of said control element through its no-pressure supply positionuntil the pressure of fluid in said one coupling is reduced to below apredetermined pressure.

7. A `drive control system includingrtwo couplings each independentlyoperable by pressurized fluid to pro- 4vide a frictional drivingconnection between a load and `a prime mover proportional to theeffective pressure of `such fluid and operable upon release of suchpressurized fluid to disconnect said load from said prime mover, a

-power control motor operable by pressurized fluid to ladjust the speedof said prime mover in proportion to `the pressure of such fluid, acontrol device operable to regulate fluid pressure for supply to saidcouplings and to said motor'and including a control element movablebetween two maximum pressure supply positions throng a no-pressuresupply position, a first valve means including a valve member shiftablebetween rst and second positions wherein said valve member is adapted toselectively supply pressurized fluid from said control device to eitherone of said couplings and at the same time to release pressurized fluidfrom theother coupling, said valve member having an intermediateposition wherein it is adapted to simultaneously release pressurizedfluid from both of said couplings, uid pressure means associated withsaid control device for shifting said first valve member to its firstand second positions to control the supply of liuid under pressure toand its release from each of said couplings in accordance with themovement of said control element to and from its nopressuresupply`position, said last-mentioned means being operable upon operation ofsaid control device element to or through its no-pressure supplyposition to shift said valve member to its-intermediate position toinsure release fluid under pressure from one of said couplings prior tothe supply of fluid under pressure to the other coupling, andinterlocking valve means operable to open said power control motor tosaid control device when said control device is supplying pressurizedfluid to said rst valve means in excess of apredetermined pressure.

8. A drive control mechanism comprising, in combination, two couplingsindependently` operable by pressurized fluid to provide a frictional-driving connection between a load and a prime mover of a torquecapacity substantially proportional ito the effective pressure of suchfluid and operable upon release of such pressurized fluid to disconnectsaid load from said prime mover, a power control motor operable bypressurized fluid -above a predetermined pressure to adjust the speed ofsaid prime mover between minimum and maximum speed limits in proportiontothe pressure ofsuch fluid, a control device operablellto regulatefluid pressure for supply to said couplings and to said motor andincluding `a control `element movable between two maximum pressuresupply positions through a 11o-pressure. supply position, said controldevice being adapted to supply pressurized fluid to one of saidcouplings sufficient to establish and maintain a substantially positivedriving connection therethrough when said control device is supplyinguid pressure in excess of said predetermined pressure to said motor, afirst valve means operable to selectively supply pressurized fluid fromsaid control device to either one of said couplings and atthe same timeto release pressurized fluid from the othercoupling, a second valvemeans operable to supply pressurized fluid from said control device tosaid motor, `fluid pressure means associated with sad control device andsaid first valve means for remotely controlling the operation of saidfirst valve means to control the supply of fluid under pressure to andits release from eachof said couplings in accordance with the movementof said control element to and from its no-pressure supply position, anda second fluid pressure means associated with said control device andsaid second valve means for remotely `controlling the operation of saidsecond valve means to control the supply of fluid under pressure to andits `release from said motor in accordance with the movement of saidcontrol element to and from its no-pressure supply position.

9. A drive control system including two couplings individuallyoperable-by fluid under pressure to provide a controllable slipfrictional driving connection between a load and a prime mover of atorque capacity substantially porportional to the effective pressure ofsuch fluid below a predetermined pressure and to provide a substantiallypositive driving connection therebetween when the pressure of such fluidis above said predetermined pressure and operable upon release of suchfluid under pressure to disconnect said load from said prime mover, apower control motor operable by fluid pressure above said predeterminedpressure to adjust the speed of said prime mover in proportion to thepressure of such fluid, a coupling control pipe connected to each ofsaid couplings, a speed control pipe connected to `said power controlmotor, a first valve means intermediate said coupling control pipes andincluding a valve member shiftable in response to a differential in thefluid pressure in said coupling control pipes to interconnect thecoupling pipe having the higher fluid pressure therein to said speedcontrol pipe, a second valve means including a second valve membershiftable between two extreme positions for selectively supplying fluidunder pressure to either `one of said coupling control pipes while atthe same time releasing fluid under pressure from the other couplingcontrol pipe and having an intermediate position for simultaneouslyreleasing fluid under pressure from both of said coupling control pipes,a double-acting motor means associated with said second valve means andoperable by uid pressure `to selectively shift said second valve membertoward either of its extreme positions, and means associated with saidsecond valve means and operable upon release of fluid pressure from saiddoubleacting motor means to shift said second Valve member Vto itsintermediate position, a control device operable to regulate fluidpressure for supplylto said couplings and to said motor through saidvalve ,means and including a control element movable betweentwo maximumpressure supply positions through a `nor-pressure supply position, andmeans associated jwith said control device and operable to selectivelysupply Afluid pressure to said double-acting motor means to control theshifting of -said second valve member to control the supply of fluidunder pressure to and its release from each of saidcouplings and saidpower control motor in accordance with the movement of saidcontrolelement to and from its no-pressure supply position, said-last-mentionedmeans being operable upon operation or" said control device element toor through its no-pressure supply position to release fluid pressurefrom said double-acting motor means to shift said second valve member toits intermediate position wherein it is adapted to simultaneouslyaeaenee release fluid under pressure from both of said Vcouplings and todelay further movement of said valve member and thereby the supply offluid under pressure to the other coupling to permit a reduction in thepressure of iluid in said one coupling below a chosen pressure.

lO. A drive control system including two couplings individually operableby uid under pressure to provide a controllable lslip frictional drivingconnection between a load and .a prime mover of a torque capacitysubstantially proportional to the effective pressurev of such fluidbelow a predetermined pressure and to provide a substantially positivedriving connection therebetween when the pressure of such iluid lisabove said predetermined pressure and operable upon release of suchiiuid under pressure to disconnect said load from said prime mover, apower control motor operable by fluid pressure above said predeterminedpressure to adjust the speed of said prime mover vin proportion to thepressure of such fluid, a coupling control pipe connected to each ofsaid couplings, a speed control pipe connected to said power controlmotor, a valve having an inlet port connected to each of said couplingcontrol pipes and an outlet port connected to said speed control pipeand including a valve member shiftable in response to a differential inthe fluid pressure in said coupling control pipes to interconnect thecoupling pipe having the higher Huid pressure therein to said speedcontrol pipe, a fourway valve including a valve member shiftable betweentwo extreme positions for selectively supplying iluid under pressure toeither one of said coupling control pipes while at the same timereleasing fluid under pressure from the other coupling control pipe andhaving an intermediate position for simultaneously releasing uid underpressure from both of said coupling control pipes, a double-acting motormeans associated with said fourway valve member and operable by fluidpressure to selectively shift said valve member toward either of itsextreme positions, and means associated with said fourway valve memberand operable upon release of lluid pressure from said double-actingmotor means to shift said four-way valve member to its intermediateposition, a control device operable to regulate fluid pressure forsupply to said couplings and to said motor through said valves andincluding a control element movable between two maximum pressure supplypositions through a nopressure supply position, and means associatedwith said control device and operable to selectively supply iluidpressure to lsaid double-acting motor means to control the shifting ofsaid valve member to control the supply of fluid under pressure to andits release from each of said couplings and said power -control motor inaccordance with the movement of said control element to and from itsno-pressure supply position, said last-mentioned means being operableupon operation of said control device element to or through itsno-pressure supply position to release uid pressure from saiddouble-acting motor means to shift said four-way valve member to itsintermediate position wherein it is adapted to simultaneouslyv releaselluid under pressure from both of -said couplings and to delay furthermovement of said valve memberand thereby the supply of fluid underpressure to the other coupling to permit a reduction in the-pres- I sureof fluid in said one coupling below a chosen pressure.

1l. Al drive control system comprising, in combination, two couplingsindividually operable by fluid under pressure to provide a controllableslip driving connection between a load and a prime mover of speed andtorque capacity substantially proportional to the effective pressure ofsuch iluid below a predetermined pressure and to provide a substantiallypositive driving connection therebetween when the pressure of such iiuidis at'or above said predetermined pressure and operable upon release ofsuch fluid under pressure to disconnect said load from said prime mover,a power control motor operable by fluid pressure above a predeterminedpressure to adjust the V24 speed of said prime mover .in proportion tothe pressure of such luid, a speed control pipe connected to said powercontrol motor, a iirst valve means operable to control the supply ofpressure fluid to and from said speed control pipe, means associatedwith said tirst valve means and operable by uid pressure to actuate saidvalve means to control the supply of pressure fluid to and from saidspeed control` pipe, a coupling control pipe connected to each of saidcouplings, a second valve means operable between two extreme controlconditions to selectively supply fluid under pressuretto either one ofsaid coupling control pipes while at the 4same time releasing iluidunder pressure from the other coupling control pipe and an intermediatecontrol condition for simultaneously releasing fluid under pressure fromboth of `said coupling control pipes,'m`otor means associated with saidsecond valve means and oper'. able by uidV pressure to selectivelyactuateV second valve means to either of its Vextreme controlconditions, and Vmeans associated with said second valve means andoperable upon release of fluid pressure from said motor means to actuatesaid second valve means to its intermediate control conditiom ar controldevice operable to progressively regulate Vfluid pressure for supply tosaid couplings and to said motor through said valve means and includinga control element movable between two maximum pressure supply positionsthrough a no-pressure supply position, and means associated with saidcontrol device and operable to selectively supply iluid pressure to saidvalve actuating means to control the actuation of said valve means tocontrol the supply of fluid under pressureto and its release from eachofsaid couplings and said power Vcontrol motor in accordance with themovement vof said control element to and fromV its no-pressure supplyposition.

12. An apparatus for controlling two individual couplings operable byfluid under pressure to provide a con'- trollable slip drivingconnection between a load and a prime mover to a degree proportional tothe pressure of such iluid below a predetermined pressure and to providea substantially positive driving connection therebetween when thepressure of such uid is above said predetermined pressure and operableupon release of such iluid under pressure to disconnect said load fromsaid prime mover, and for also controlling a power control motoroperable by Huid pressure to adjust the speed of said prime moverbetween minimum and maximum speed limits in proportion to the pressureof such fluid above said predetermined pressure, comprising incombination with said couplings and motor, a coupling control pipeconnected to each of said couplings, a speed control pipe for said powercontrol motor, a two-way check valve having an inlet port connected toeach of said coupling control pipes and an outlet port connected to saidspeed controlY pipe and including a valve member shiftable in responseto a iluid pressure differential in said coupling control pipes tointerconnect the coupling pipe having the higher fluid pressure thereinto said speed control pipe, a four-way valve means including a valvemember shiftable between two extreme positions for selectively supplyingfluid under pressure to either one of said coupling control pipes whileat the same time releasing fluid under pressure from the other couplingcontrol pipe and having an intermediate position for simultaneouslyreleasing iiuid under` pressure from both Vof said coupling controlpipes, a doubleacting motor means associated with said four-way valvemember and operable by. iluid pressure to selectively shift said valvemember toward its extreme positions, means associated with said four-wayvalve member and operable upon release fluid pressure from said motormeansto shift said four-way valve member to its intermediate positions,and a control device including a control element movable from ano-pressure supply position to either of two full pressure supplypositions to progressively regulate the pressure of uid supplied throughsaid four-Way valve means to said couplings and motor, and shift valvemeans `l toperable inV accordance with `*movement of 'said contr-olvelement to and from its no-pressure supply position to selectivelycontrol the supply and release of iluid pressure --to-and from saiddouble-acting motor means to thereby .control the shifting of saidfour-way valve member to control the supply of fluid under pressure toand its release from each of said couplings and said motor.

i 13. A mechanism for controlling power transmission .between a load anda prime mover comprising, in combination, a power control motor operableby liuid pres- `fsure above a predetermined pressure to adjust the speedof said prime mover in proportion to the pressure of such `fluid, twocouplings individually operable by duid under pressure to provide acontrollable slip driving connection .between said load and said primemover of a torque capacity substantially proportional to the effectivepressure of such fluid below saidpredetermined pressure and Ato, providea substantially positive driving connection therebetween when thepressure of such fluid is above said predetermined pressure and operableupon release of such .fluid under pressure to disconnect said load fromsaid tprime mover, a speed control pipe connected to said ,power controlmotor, a first flow control means associated `with said speedcontrolpipe and adapted to restrict 4theiflowofA fluid to said speed`control motor and to permit theunrestricted venting of fluid from saidmotor, a coupling control pipe connected to each of said couplings, afirst valve-means intermediate said coupling control pipes and operablein response to a differential in the iluid Vpressure in said couplingcontrol pipes to interconnect the ,coupling `pipe having the higherfluid pressure therein Ato said speed `control pipe, a second valvemeans operable between two extreme control conditions wherein fluidlunder pressure is selectively supplied to either one of said .couplingcontrol pipes while at `the same time releasing fluid under pressurefrom the othercoupling control pipe and an intermediate controlcondition wherein fluid under pressure is simultaneously released fromboth of said `coupling control pipes, motor means associated with saidsecond valve means and operable by fluid pressure to y selectivelyactuate said second valve means toward either .of its extreme controlconditions and operable upon `release -of fluid pressure therefrom toshift said second `valve means to .its intermediate control condition, a`control `device .operable to progressively regulate fluid pressure forsupply to said couplings and to said motor through said valve means andincluding a control element movable between two maximum speed and loadpressure supply positions through a neutral no-pressure supply position,a pressure supply pipe interconnecting said device and said second valvemeans, a second flow control means associated with said last-mentionedpipe and adapted to restrict the ow of fluid to said second ,valve meansand to Vpermit the relatively unrestricted `venting `of fluid from saidsecond valve means, a third valve means associated with said controldevice and operable to selectively supply and release fluid pressure 4toand from said motor means to control theactuationf of said ,second valvemeans in accordance with the movement of Isaid` control element to andfrom its no-pressure supply -neutralpositiom and third flow controlmeans intermedi- `ate said third valve means and said motor means and)adapted to restrict the fiow of fluid towards said motor means ,and topermit the relatively unrestricted venting thereof `whereby operation ofsaid control device element to or through vits no-pressure supplyposition causes said third valve means to quickly vent fluid pressurefrom said `,motor means thereby causingA said motormeans to actuate saidsecond valve means from` one of its eXtreme 'control conditions to itsintermediate control conditions twhe'reinit is adapted to release iluidunder` pressure from the previously engaged one of said couplings and todelay ractuationof said second valve means toits other extremecontrol,condition `and thereby the` supply of uid under `pressuretotheother ctmplingto` permit `a reduction in pressure and to provide asubstantially positive Vdriving connection therebetween when thepressure of suchuid is above said predetermined pressure andoperableupon release of such iluidunder pressure toV disconnect saidload from said prime mover, a speed control pipe connected to said powercontrol motor, a first iiow control means associated with said speedcontrol pipe and adapted to Arestrict the ow of fluid to said speedcontrol motor and to permit the unrestricted venting of fluid from saidmotor, a coupling control pipe connected to each of said couplings, afirst valve means intermediate said coupling control pipes and operablein response to a differential inthe iluid pressure in said couplingcontrol pipes to interconnect the coupling pipe having the higher fluidpressure therein to said speed control pipe, a second valve `meansoperable between two operating conditions where- ,in` uid under`pressure is alternatively supplied to one `of said coupling controlpipes while at the same time releasing fluid under pressure from theother coupling control pipe and an intermediate operating conditionwherein fluid under pressure is simultaneously released Ifrom both Yofsaid coupling control pipes, motor means associated withv said secondvalve means and operable by fluid pressure to selectively actuate saidsecond valve means toward either of its extreme operating conditions andoperable upon release of fluid pressure therefrom `to shift said secondvalve means to its intermediate operating condition, a control deviceoperable to progressively regulate fluid pressure for supply to saidcouplings and to said motor through said Valve means and includ- -ing acontrol element movable between two maximum speed and load pressuresupply positions through a neutral no-pressure supply position, apressure supply pipe interconnecting said device and said second valvemeans, a second ow control means associated with said last- Amentionedpipe and adapted to restrict the flow of fluid to said second valvemeans land to permit the relatively unrestricted venting of fluid fromsaid second valve means, and a third valve means associated with saidcontrol device land operable to selectively supply and release iluidpressure to and from said motor means to control the actuation of saidsecond valve means in accord- .ance with the movement of said controlelement to and from its `no-pressure supply neutral position.

15. In a mechanism for controlling power transmis- VAsion between a loadand a prime mover, the combination comprising a power control motoroperable by fluid pressure above a predetermined pressure to adjust the`speed of said prime mover in proportion to the pressure of such uid,two couplings individually operable by fluid under pressure to provide acontrollable slip driving connection between said load and prime mover,of a speed and torque capacity substantially proportional to theeffective pressure of such duid below said predeterminedpressure and toprovide a substantially positive `driving `connection therebetween whenthe pressure ,of

.suchfluid is above said predetermined pressure and operable uponrelease of such fluid Linder pressure to disconnect said load from saidprime mover, a speed control pipe connected to said power control motor,a cou- .plingrcontrolpipe connected to each of said couplings,

a first ,valve means intermediate said coupling `control pipes andoperable in response `to a differential in .the uidpressure in` saidcoupling control pipestofintercon- 27 Y Y nect the coupling pipe havingthe higher fluid pressure therein to said speed control pipe, -a secondvalve means operable between two extreme operational conditions whereinfluid under pressure is selectively supplied to either on of saidcoupling control pipes while at the same time releasing liuid underpressure from the other coupling control pipe and an intermediateoperational condition wherein both of said coupling control pipes aresimultaneously vented, motor means associated with said second valvemeans andk operable by fluid pressure to selectively actuate said secondvalve means toward either of its extreme operational conditions andoperable upon release of tluid pressure therefrom to shift said secondvalve means to its intermediate operational condition,

fa control device operable to progressively regulate uid pressure forsupply to said couplings and to said motor through said valve means andincluding a control elementmovable between two maximum speed and loadpressure supply positions through a neutral no-pressure supply position,Va pressure supply pipe interconnecting said device and said secondvalve means, and a third valve means associated with said control deviceand operable to selectively control the supply and release fluidpressure to `and from said motor means to control the actuation of saidsecond valve means in accordance with the movement of said controlelement to and from its nopressure supply neutral position.

16. The combination set forth in claim and including a flow controlmeans intermediate said third valve means and saidmotor means andadapted to restrict the flow of Huid towards said motor means and topermit the relatively unrestricted venting thereof whereby operation ofsaid control element to or through its nopressure supply position causessaid third valve means to quickly vent fluid pressure from said motor`means thereby causing said motor means to actuate'said second valvemeans to its intermediate operational condition wherein it is adapted torelease fiuid 'under pressure from one of said couplings, said ilowcontrol means delaying the supply of actuating pressure fluid to saidmotor means to effect further movement of said valve member towardsits`other extreme operational condition thereby delaying the supply offluid under pressure to the other coupling to permit a reduction in thepressure of uid in said one coupling below a chosen pressure.

17. The combination as set forth in claim 15 and including interlockingvalve means intermediate said third valve means and said motor means andoperable in response to the pressure of iiuid supplied to either one ofsaid couplings to permit relatively unrestricted venting 'of said motormeans to return said second valve means to its intermediate operationalcondition from one of said extreme operational conditions upon actuationof said control element to or through its no-pressure supply positionand to prevent the supply of tluid under pressure to said motor means toshift said second valve means towards the other of its extremeoperational conditions and thereby the Supply of pressure to the otherof said couplings until the pressure of said one coupling is reduced toor below said predetermined pressure.

18. The `combination set forth in claim 15 and including a now controlmeans intermediate said control device and said lsecond valve means yandadapted to restrict the ow of control device regulated pressure fluidtowards said couplings and power control motor and -to permit therelatively unrestricted venting of fluid therefrom, and relay valvemeans operable to bypass said ow control means in response to the supplyof Huid above said predetermined pressure to said second valve meansthereby permtiting the relatively unrestricted supply of control deviceregulated pressure uid through said second valve means to one of saidcouplings and said power control motor after a postve driving connectionnas been initially established through said one coupling.

19. In a mechanism for controlling transmission of power between a loadand a prime mover, the combina- 28 tion comprising aprime mover controlincludinga motor operable by fluid pressure to adjust the speed andtorque capacity of said prime mover in proportion' toA the pressure ofsuch fluid, a pipe connected to said motor, a first valve meansassociated with said pipe operable to control fluid liow therethrough,and means lassociated with/ Isaid first valve means and operable by uidpressure to actuate said valve means to control the supply of pressurefluid to and from* said power control motor, two couplingsindividuallyoperable by uid under pressure to provide a controllable slip drivingconnection between said load and prime mover of a speed and torquecasure is selectively supplied to either one ofsaid couplingv vconnected pipes while at the same time releasing fluid under pressurefrom the other coupling connected pipe and an intermediate operationalcondition wherein both of said coupling connected pipes are`simultaneously vented, double-acting motor means associated with saidsecond valve means and operable by fluid pressure supplied to oppositeends thereof to selectively actuate said second valve means towardeither of its altern-ative operational conditions and operable uponrelease of fluid pressure from both ends thereof to shift said secondvalve means to its intermediate operational condition, a control deviceoperable to progressively regulate uid pressure for supply to saidcouplings and tosaid motor through said rst and second valve means andincluding a control element movable between two maximum speed and loadpressure supply positions through a neutral no-pressure supply position,a pressure supply pipe interconnecting said device and said second valvemeans, a third valve means associated with said control device andoperable to selectively control the supply and release fluid pressure toand from the opposite ends of said motor means to control the actuationof said second valve means in accordance with the movement of saidcontrol element to and vfrom its no-pressure supply neutral position,and two pipes interconnecting said third valve means to opposite ends ofsaid motor means.

20. In a mechanism for controlling transmission of power between a loadand a prime mover, the combination comprising apower control motoroperable by uid pressure to adjust the speed and torque capacity of saidprime mover in proportion .to the pressure of such iiuid, two couplingsindividually operable by liuid under pressure to provide a controllableslip driving connection between said load and prime mover of a speed andtorque capacity substantially proportional to the elective pressure ofsuch uid below a predetermined pressure and to provide a substantiallypositive driving connection therebetween when theY pressure of such uidis above said predetermined pressure and operable upon release of suchfluid under pressure to disconnect said load from said prime mover, aspeed control pipe connected to said power control motor, a rst valvemeans operable to control the supply of pressure fluid to and from saidspeed control pipe, means associated with saidrst valve means andoperable by uid pressure to actuate said valve means to control thesupply of pressure uid to and from said speed control pipe, a couplingcontrol pipe connected to each of said couplings, second valve meansoperable between two extreme operational conditions wherein fluid underpressure is selectively supplied to either one of said coupling controlpipes while at the same timoreleasing fluid under pressure from theotherA coupling control pipe and an intermediate'operational condition

